diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index bcf3a78f052c5..492ad331b2d86 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -1015,6 +1015,22 @@ namespace ts {
         const builtinGlobals = createSymbolTable();
         builtinGlobals.set(undefinedSymbol.escapedName, undefinedSymbol);
 
+        // Extensions suggested for path imports when module resolution is node12 or higher.
+        // The first element of each tuple is the extension a file has.
+        // The second element of each tuple is the extension that should be used in a path import.
+        // e.g. if we want to import file `foo.mts`, we should write `import {} from "./foo.mjs".
+        const suggestedExtensions: [string, string][] = [
+            [".mts", ".mjs"],
+            [".ts", ".js"],
+            [".cts", ".cjs"],
+            [".mjs", ".mjs"],
+            [".js", ".js"],
+            [".cjs", ".cjs"],
+            [".tsx", compilerOptions.jsx === JsxEmit.Preserve ? ".jsx" : ".js"],
+            [".jsx", ".jsx"],
+            [".json", ".json"],
+        ];
+
         initializeTypeChecker();
 
         return checker;
@@ -3417,7 +3433,7 @@ namespace ts {
                     (isModuleDeclaration(location) ? location : location.parent && isModuleDeclaration(location.parent) && location.parent.name === location ? location.parent : undefined)?.name ||
                     (isLiteralImportTypeNode(location) ? location : undefined)?.argument.literal;
             const mode = contextSpecifier && isStringLiteralLike(contextSpecifier) ? getModeForUsageLocation(currentSourceFile, contextSpecifier) : currentSourceFile.impliedNodeFormat;
-            const resolvedModule = getResolvedModule(currentSourceFile, moduleReference, mode)!; // TODO: GH#18217
+            const resolvedModule = getResolvedModule(currentSourceFile, moduleReference, mode);
             const resolutionDiagnostic = resolvedModule && getResolutionDiagnostic(compilerOptions, resolvedModule);
             const sourceFile = resolvedModule && !resolutionDiagnostic && host.getSourceFile(resolvedModule.resolvedFileName);
             if (sourceFile) {
@@ -3460,10 +3476,10 @@ namespace ts {
             if (resolvedModule && !resolutionExtensionIsTSOrJson(resolvedModule.extension) && resolutionDiagnostic === undefined || resolutionDiagnostic === Diagnostics.Could_not_find_a_declaration_file_for_module_0_1_implicitly_has_an_any_type) {
                 if (isForAugmentation) {
                     const diag = Diagnostics.Invalid_module_name_in_augmentation_Module_0_resolves_to_an_untyped_module_at_1_which_cannot_be_augmented;
-                    error(errorNode, diag, moduleReference, resolvedModule.resolvedFileName);
+                    error(errorNode, diag, moduleReference, resolvedModule!.resolvedFileName);
                 }
                 else {
-                    errorOnImplicitAnyModule(/*isError*/ noImplicitAny && !!moduleNotFoundError, errorNode, resolvedModule, moduleReference);
+                    errorOnImplicitAnyModule(/*isError*/ noImplicitAny && !!moduleNotFoundError, errorNode, resolvedModule!, moduleReference);
                 }
                 // Failed imports and untyped modules are both treated in an untyped manner; only difference is whether we give a diagnostic first.
                 return undefined;
@@ -3484,6 +3500,10 @@ namespace ts {
                 }
                 else {
                     const tsExtension = tryExtractTSExtension(moduleReference);
+                    const isExtensionlessRelativePathImport = pathIsRelative(moduleReference) && !hasExtension(moduleReference);
+                    const moduleResolutionKind = getEmitModuleResolutionKind(compilerOptions);
+                    const resolutionIsNode12OrNext = moduleResolutionKind === ModuleResolutionKind.Node12 ||
+                        moduleResolutionKind === ModuleResolutionKind.NodeNext;
                     if (tsExtension) {
                         const diag = Diagnostics.An_import_path_cannot_end_with_a_0_extension_Consider_importing_1_instead;
                         const importSourceWithoutExtension = removeExtension(moduleReference, tsExtension);
@@ -3503,6 +3523,18 @@ namespace ts {
                         hasJsonModuleEmitEnabled(compilerOptions)) {
                         error(errorNode, Diagnostics.Cannot_find_module_0_Consider_using_resolveJsonModule_to_import_module_with_json_extension, moduleReference);
                     }
+                    else if (mode === ModuleKind.ESNext && resolutionIsNode12OrNext && isExtensionlessRelativePathImport) {
+                        const absoluteRef = getNormalizedAbsolutePath(moduleReference, getDirectoryPath(currentSourceFile.path));
+                        const suggestedExt = suggestedExtensions.find(([actualExt, _importExt]) => host.fileExists(absoluteRef + actualExt))?.[1];
+                        if (suggestedExt) {
+                            error(errorNode,
+                                Diagnostics.Relative_import_paths_need_explicit_file_extensions_in_EcmaScript_imports_when_moduleResolution_is_node12_or_nodenext_Did_you_mean_0,
+                                moduleReference + suggestedExt);
+                        }
+                        else {
+                            error(errorNode, Diagnostics.Relative_import_paths_need_explicit_file_extensions_in_EcmaScript_imports_when_moduleResolution_is_node12_or_nodenext_Consider_adding_an_extension_to_the_import_path);
+                        }
+                    }
                     else {
                         error(errorNode, moduleNotFoundError, moduleReference);
                     }
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index a40439d012afd..267a8efc4799b 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -3341,6 +3341,14 @@
         "category": "Error",
         "code": 2833
     },
+    "Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.": {
+        "category": "Error",
+        "code": 2834
+    },
+    "Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean '{0}'?": {
+        "category": "Error",
+        "code": 2835
+    },
 
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index a5b143e06f3bd..4c339b18fc495 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -5983,7 +5983,7 @@ namespace ts {
     export enum ModuleResolutionKind {
         Classic  = 1,
         NodeJs   = 2,
-        // Starting with node12, node's module resolver has significant departures from tranditional cjs resolution
+        // Starting with node12, node's module resolver has significant departures from traditional cjs resolution
         // to better support ecmascript modules and their use within node - more features are still being added, so
         // we can expect it to change over time, and as such, offer both a `NodeNext` moving resolution target, and a `Node12`
         // version-anchored resolution target
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension1.errors.txt b/tests/baselines/reference/moduleResolutionWithoutExtension1.errors.txt
new file mode 100644
index 0000000000000..5f3cbbc121cfb
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension1.errors.txt
@@ -0,0 +1,18 @@
+/src/bar.mts(2,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './foo.mjs'?
+/src/bar.mts(3,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+
+
+==== /src/foo.mts (0 errors) ====
+    export function foo() {
+        return "";
+    }
+    
+==== /src/bar.mts (2 errors) ====
+    // Extensionless relative path ES import in an ES module
+    import { foo } from "./foo"; // should error, suggest adding ".mjs"
+                        ~~~~~~~
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './foo.mjs'?
+    import { baz } from "./baz"; // should error, ask for extension, no extension suggestion
+                        ~~~~~~~
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension1.js b/tests/baselines/reference/moduleResolutionWithoutExtension1.js
new file mode 100644
index 0000000000000..39f3af1bcb538
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension1.js
@@ -0,0 +1,19 @@
+//// [tests/cases/conformance/externalModules/moduleResolutionWithoutExtension1.ts] ////
+
+//// [foo.mts]
+export function foo() {
+    return "";
+}
+
+//// [bar.mts]
+// Extensionless relative path ES import in an ES module
+import { foo } from "./foo"; // should error, suggest adding ".mjs"
+import { baz } from "./baz"; // should error, ask for extension, no extension suggestion
+
+
+//// [foo.mjs]
+export function foo() {
+    return "";
+}
+//// [bar.mjs]
+export {};
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension1.symbols b/tests/baselines/reference/moduleResolutionWithoutExtension1.symbols
new file mode 100644
index 0000000000000..5b3588c39019d
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension1.symbols
@@ -0,0 +1,15 @@
+=== /src/foo.mts ===
+export function foo() {
+>foo : Symbol(foo, Decl(foo.mts, 0, 0))
+
+    return "";
+}
+
+=== /src/bar.mts ===
+// Extensionless relative path ES import in an ES module
+import { foo } from "./foo"; // should error, suggest adding ".mjs"
+>foo : Symbol(foo, Decl(bar.mts, 1, 8))
+
+import { baz } from "./baz"; // should error, ask for extension, no extension suggestion
+>baz : Symbol(baz, Decl(bar.mts, 2, 8))
+
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension1.types b/tests/baselines/reference/moduleResolutionWithoutExtension1.types
new file mode 100644
index 0000000000000..79b5c11773d59
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension1.types
@@ -0,0 +1,16 @@
+=== /src/foo.mts ===
+export function foo() {
+>foo : () => string
+
+    return "";
+>"" : ""
+}
+
+=== /src/bar.mts ===
+// Extensionless relative path ES import in an ES module
+import { foo } from "./foo"; // should error, suggest adding ".mjs"
+>foo : any
+
+import { baz } from "./baz"; // should error, ask for extension, no extension suggestion
+>baz : any
+
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension2.errors.txt b/tests/baselines/reference/moduleResolutionWithoutExtension2.errors.txt
new file mode 100644
index 0000000000000..e541ad83a67cd
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension2.errors.txt
@@ -0,0 +1,8 @@
+/src/buzz.mts(2,22): error TS2307: Cannot find module './foo' or its corresponding type declarations.
+
+
+==== /src/buzz.mts (1 errors) ====
+    // Extensionless relative path cjs import in an ES module
+    import foo = require("./foo"); // should error, should not ask for extension
+                         ~~~~~~~
+!!! error TS2307: Cannot find module './foo' or its corresponding type declarations.
\ No newline at end of file
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension2.js b/tests/baselines/reference/moduleResolutionWithoutExtension2.js
new file mode 100644
index 0000000000000..f5d7cf95c75ee
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension2.js
@@ -0,0 +1,6 @@
+//// [buzz.mts]
+// Extensionless relative path cjs import in an ES module
+import foo = require("./foo"); // should error, should not ask for extension
+
+//// [buzz.mjs]
+export {};
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension2.symbols b/tests/baselines/reference/moduleResolutionWithoutExtension2.symbols
new file mode 100644
index 0000000000000..c10eaa8a5b21b
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension2.symbols
@@ -0,0 +1,5 @@
+=== /src/buzz.mts ===
+// Extensionless relative path cjs import in an ES module
+import foo = require("./foo"); // should error, should not ask for extension
+>foo : Symbol(foo, Decl(buzz.mts, 0, 0))
+
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension2.types b/tests/baselines/reference/moduleResolutionWithoutExtension2.types
new file mode 100644
index 0000000000000..89d7b057c8fae
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension2.types
@@ -0,0 +1,5 @@
+=== /src/buzz.mts ===
+// Extensionless relative path cjs import in an ES module
+import foo = require("./foo"); // should error, should not ask for extension
+>foo : any
+
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension3.errors.txt b/tests/baselines/reference/moduleResolutionWithoutExtension3.errors.txt
new file mode 100644
index 0000000000000..0c753a1029900
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension3.errors.txt
@@ -0,0 +1,14 @@
+/src/bar.mts(2,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './foo.jsx'?
+
+
+==== /src/foo.tsx (0 errors) ====
+    export function foo() {
+        return "";
+    }
+    
+==== /src/bar.mts (1 errors) ====
+    // Extensionless relative path ES import in an ES module
+    import { foo } from "./foo"; // should error, suggest adding ".jsx"
+                        ~~~~~~~
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './foo.jsx'?
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension3.js b/tests/baselines/reference/moduleResolutionWithoutExtension3.js
new file mode 100644
index 0000000000000..964402755a434
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension3.js
@@ -0,0 +1,22 @@
+//// [tests/cases/conformance/externalModules/moduleResolutionWithoutExtension3.ts] ////
+
+//// [foo.tsx]
+export function foo() {
+    return "";
+}
+
+//// [bar.mts]
+// Extensionless relative path ES import in an ES module
+import { foo } from "./foo"; // should error, suggest adding ".jsx"
+
+
+//// [foo.jsx]
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.foo = void 0;
+function foo() {
+    return "";
+}
+exports.foo = foo;
+//// [bar.mjs]
+export {};
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension3.symbols b/tests/baselines/reference/moduleResolutionWithoutExtension3.symbols
new file mode 100644
index 0000000000000..707433d072a60
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension3.symbols
@@ -0,0 +1,12 @@
+=== /src/foo.tsx ===
+export function foo() {
+>foo : Symbol(foo, Decl(foo.tsx, 0, 0))
+
+    return "";
+}
+
+=== /src/bar.mts ===
+// Extensionless relative path ES import in an ES module
+import { foo } from "./foo"; // should error, suggest adding ".jsx"
+>foo : Symbol(foo, Decl(bar.mts, 1, 8))
+
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension3.types b/tests/baselines/reference/moduleResolutionWithoutExtension3.types
new file mode 100644
index 0000000000000..a94a6890b6898
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension3.types
@@ -0,0 +1,13 @@
+=== /src/foo.tsx ===
+export function foo() {
+>foo : () => string
+
+    return "";
+>"" : ""
+}
+
+=== /src/bar.mts ===
+// Extensionless relative path ES import in an ES module
+import { foo } from "./foo"; // should error, suggest adding ".jsx"
+>foo : any
+
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension4.errors.txt b/tests/baselines/reference/moduleResolutionWithoutExtension4.errors.txt
new file mode 100644
index 0000000000000..afd24269d69bc
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension4.errors.txt
@@ -0,0 +1,14 @@
+/src/bar.mts(2,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './foo.js'?
+
+
+==== /src/foo.tsx (0 errors) ====
+    export function foo() {
+        return "";
+    }
+    
+==== /src/bar.mts (1 errors) ====
+    // Extensionless relative path ES import in an ES module
+    import { foo } from "./foo"; // should error, suggest adding ".js"
+                        ~~~~~~~
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './foo.js'?
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension4.js b/tests/baselines/reference/moduleResolutionWithoutExtension4.js
new file mode 100644
index 0000000000000..b67ea6284a3ff
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension4.js
@@ -0,0 +1,22 @@
+//// [tests/cases/conformance/externalModules/moduleResolutionWithoutExtension4.ts] ////
+
+//// [foo.tsx]
+export function foo() {
+    return "";
+}
+
+//// [bar.mts]
+// Extensionless relative path ES import in an ES module
+import { foo } from "./foo"; // should error, suggest adding ".js"
+
+
+//// [foo.js]
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.foo = void 0;
+function foo() {
+    return "";
+}
+exports.foo = foo;
+//// [bar.mjs]
+export {};
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension4.symbols b/tests/baselines/reference/moduleResolutionWithoutExtension4.symbols
new file mode 100644
index 0000000000000..ba19300835274
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension4.symbols
@@ -0,0 +1,12 @@
+=== /src/foo.tsx ===
+export function foo() {
+>foo : Symbol(foo, Decl(foo.tsx, 0, 0))
+
+    return "";
+}
+
+=== /src/bar.mts ===
+// Extensionless relative path ES import in an ES module
+import { foo } from "./foo"; // should error, suggest adding ".js"
+>foo : Symbol(foo, Decl(bar.mts, 1, 8))
+
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension4.types b/tests/baselines/reference/moduleResolutionWithoutExtension4.types
new file mode 100644
index 0000000000000..e72345bda427d
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension4.types
@@ -0,0 +1,13 @@
+=== /src/foo.tsx ===
+export function foo() {
+>foo : () => string
+
+    return "";
+>"" : ""
+}
+
+=== /src/bar.mts ===
+// Extensionless relative path ES import in an ES module
+import { foo } from "./foo"; // should error, suggest adding ".js"
+>foo : any
+
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension5.errors.txt b/tests/baselines/reference/moduleResolutionWithoutExtension5.errors.txt
new file mode 100644
index 0000000000000..b4b0a89ae974f
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension5.errors.txt
@@ -0,0 +1,8 @@
+/src/buzz.mts(2,8): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+
+
+==== /src/buzz.mts (1 errors) ====
+    // Extensionless relative path dynamic import in an ES module
+    import("./foo").then(x => x); // should error, ask for extension
+           ~~~~~~~
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
\ No newline at end of file
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension5.js b/tests/baselines/reference/moduleResolutionWithoutExtension5.js
new file mode 100644
index 0000000000000..b79c4d0d548b0
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension5.js
@@ -0,0 +1,7 @@
+//// [buzz.mts]
+// Extensionless relative path dynamic import in an ES module
+import("./foo").then(x => x); // should error, ask for extension
+
+//// [buzz.mjs]
+// Extensionless relative path dynamic import in an ES module
+import("./foo").then(x => x); // should error, ask for extension
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension5.symbols b/tests/baselines/reference/moduleResolutionWithoutExtension5.symbols
new file mode 100644
index 0000000000000..d66bb3d0fff5b
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension5.symbols
@@ -0,0 +1,8 @@
+=== /src/buzz.mts ===
+// Extensionless relative path dynamic import in an ES module
+import("./foo").then(x => x); // should error, ask for extension
+>import("./foo").then : Symbol(Promise.then, Decl(lib.es5.d.ts, --, --))
+>then : Symbol(Promise.then, Decl(lib.es5.d.ts, --, --))
+>x : Symbol(x, Decl(buzz.mts, 1, 21))
+>x : Symbol(x, Decl(buzz.mts, 1, 21))
+
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension5.types b/tests/baselines/reference/moduleResolutionWithoutExtension5.types
new file mode 100644
index 0000000000000..d18f5276dba1c
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension5.types
@@ -0,0 +1,12 @@
+=== /src/buzz.mts ===
+// Extensionless relative path dynamic import in an ES module
+import("./foo").then(x => x); // should error, ask for extension
+>import("./foo").then(x => x) : Promise<any>
+>import("./foo").then : <TResult1 = any, TResult2 = never>(onfulfilled?: (value: any) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
+>import("./foo") : Promise<any>
+>"./foo" : "./foo"
+>then : <TResult1 = any, TResult2 = never>(onfulfilled?: (value: any) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
+>x => x : (x: any) => any
+>x : any
+>x : any
+
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension6.errors.txt b/tests/baselines/reference/moduleResolutionWithoutExtension6.errors.txt
new file mode 100644
index 0000000000000..267a4cd5a0a53
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension6.errors.txt
@@ -0,0 +1,10 @@
+/src/bar.cts(4,21): error TS2307: Cannot find module './foo' or its corresponding type declarations.
+
+
+==== /src/bar.cts (1 errors) ====
+    // Extensionless relative path import statement in a cjs module
+    // Import statements are not allowed in cjs files,
+    // but other errors should not assume that they are allowed
+    import { foo } from "./foo"; // should error, should not ask for extension
+                        ~~~~~~~
+!!! error TS2307: Cannot find module './foo' or its corresponding type declarations.
\ No newline at end of file
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension6.js b/tests/baselines/reference/moduleResolutionWithoutExtension6.js
new file mode 100644
index 0000000000000..0df0659f2d516
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension6.js
@@ -0,0 +1,9 @@
+//// [bar.cts]
+// Extensionless relative path import statement in a cjs module
+// Import statements are not allowed in cjs files,
+// but other errors should not assume that they are allowed
+import { foo } from "./foo"; // should error, should not ask for extension
+
+//// [bar.cjs]
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension6.symbols b/tests/baselines/reference/moduleResolutionWithoutExtension6.symbols
new file mode 100644
index 0000000000000..0e0f1e7963667
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension6.symbols
@@ -0,0 +1,7 @@
+=== /src/bar.cts ===
+// Extensionless relative path import statement in a cjs module
+// Import statements are not allowed in cjs files,
+// but other errors should not assume that they are allowed
+import { foo } from "./foo"; // should error, should not ask for extension
+>foo : Symbol(foo, Decl(bar.cts, 3, 8))
+
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension6.types b/tests/baselines/reference/moduleResolutionWithoutExtension6.types
new file mode 100644
index 0000000000000..7b87af3ccf3b3
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension6.types
@@ -0,0 +1,7 @@
+=== /src/bar.cts ===
+// Extensionless relative path import statement in a cjs module
+// Import statements are not allowed in cjs files,
+// but other errors should not assume that they are allowed
+import { foo } from "./foo"; // should error, should not ask for extension
+>foo : any
+
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension7.errors.txt b/tests/baselines/reference/moduleResolutionWithoutExtension7.errors.txt
new file mode 100644
index 0000000000000..0ff660b3418e3
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension7.errors.txt
@@ -0,0 +1,8 @@
+/src/bar.cts(2,22): error TS2307: Cannot find module './foo' or its corresponding type declarations.
+
+
+==== /src/bar.cts (1 errors) ====
+    // Extensionless relative path cjs import in a cjs module
+    import foo = require("./foo"); // should error, should not ask for extension
+                         ~~~~~~~
+!!! error TS2307: Cannot find module './foo' or its corresponding type declarations.
\ No newline at end of file
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension7.js b/tests/baselines/reference/moduleResolutionWithoutExtension7.js
new file mode 100644
index 0000000000000..949b36a9d1da8
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension7.js
@@ -0,0 +1,7 @@
+//// [bar.cts]
+// Extensionless relative path cjs import in a cjs module
+import foo = require("./foo"); // should error, should not ask for extension
+
+//// [bar.cjs]
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension7.symbols b/tests/baselines/reference/moduleResolutionWithoutExtension7.symbols
new file mode 100644
index 0000000000000..4397e9a2e294f
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension7.symbols
@@ -0,0 +1,5 @@
+=== /src/bar.cts ===
+// Extensionless relative path cjs import in a cjs module
+import foo = require("./foo"); // should error, should not ask for extension
+>foo : Symbol(foo, Decl(bar.cts, 0, 0))
+
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension7.types b/tests/baselines/reference/moduleResolutionWithoutExtension7.types
new file mode 100644
index 0000000000000..1ebf99baf94cb
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension7.types
@@ -0,0 +1,5 @@
+=== /src/bar.cts ===
+// Extensionless relative path cjs import in a cjs module
+import foo = require("./foo"); // should error, should not ask for extension
+>foo : any
+
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension8.errors.txt b/tests/baselines/reference/moduleResolutionWithoutExtension8.errors.txt
new file mode 100644
index 0000000000000..c990522c6c707
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension8.errors.txt
@@ -0,0 +1,8 @@
+/src/bar.cts(2,8): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+
+
+==== /src/bar.cts (1 errors) ====
+    // Extensionless relative path dynamic import in a cjs module
+    import("./foo").then(x => x); // should error, ask for extension
+           ~~~~~~~
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
\ No newline at end of file
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension8.js b/tests/baselines/reference/moduleResolutionWithoutExtension8.js
new file mode 100644
index 0000000000000..593f3668b3c73
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension8.js
@@ -0,0 +1,7 @@
+//// [bar.cts]
+// Extensionless relative path dynamic import in a cjs module
+import("./foo").then(x => x); // should error, ask for extension
+
+//// [bar.cjs]
+// Extensionless relative path dynamic import in a cjs module
+import("./foo").then(x => x); // should error, ask for extension
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension8.symbols b/tests/baselines/reference/moduleResolutionWithoutExtension8.symbols
new file mode 100644
index 0000000000000..deded53a4ec65
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension8.symbols
@@ -0,0 +1,8 @@
+=== /src/bar.cts ===
+// Extensionless relative path dynamic import in a cjs module
+import("./foo").then(x => x); // should error, ask for extension
+>import("./foo").then : Symbol(Promise.then, Decl(lib.es5.d.ts, --, --))
+>then : Symbol(Promise.then, Decl(lib.es5.d.ts, --, --))
+>x : Symbol(x, Decl(bar.cts, 1, 21))
+>x : Symbol(x, Decl(bar.cts, 1, 21))
+
diff --git a/tests/baselines/reference/moduleResolutionWithoutExtension8.types b/tests/baselines/reference/moduleResolutionWithoutExtension8.types
new file mode 100644
index 0000000000000..fdde64edc490c
--- /dev/null
+++ b/tests/baselines/reference/moduleResolutionWithoutExtension8.types
@@ -0,0 +1,12 @@
+=== /src/bar.cts ===
+// Extensionless relative path dynamic import in a cjs module
+import("./foo").then(x => x); // should error, ask for extension
+>import("./foo").then(x => x) : Promise<any>
+>import("./foo").then : <TResult1 = any, TResult2 = never>(onfulfilled?: (value: any) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
+>import("./foo") : Promise<any>
+>"./foo" : "./foo"
+>then : <TResult1 = any, TResult2 = never>(onfulfilled?: (value: any) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
+>x => x : (x: any) => any
+>x : any
+>x : any
+
diff --git a/tests/baselines/reference/nodeModules1(module=node12).errors.txt b/tests/baselines/reference/nodeModules1(module=node12).errors.txt
index 6398640a86946..724e3b73ed7b2 100644
--- a/tests/baselines/reference/nodeModules1(module=node12).errors.txt
+++ b/tests/baselines/reference/nodeModules1(module=node12).errors.txt
@@ -15,70 +15,70 @@ tests/cases/conformance/node/index.cts(59,22): error TS1471: Module './subfolder
 tests/cases/conformance/node/index.cts(60,22): error TS1471: Module './subfolder2/another/' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.cts(61,22): error TS1471: Module './subfolder2/another/index' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.cts(75,21): error TS2307: Cannot find module './' or its corresponding type declarations.
-tests/cases/conformance/node/index.cts(76,21): error TS2307: Cannot find module './index' or its corresponding type declarations.
-tests/cases/conformance/node/index.cts(77,21): error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
-tests/cases/conformance/node/index.cts(78,21): error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
-tests/cases/conformance/node/index.cts(79,21): error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
-tests/cases/conformance/node/index.cts(80,21): error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
-tests/cases/conformance/node/index.cts(81,21): error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
-tests/cases/conformance/node/index.cts(82,21): error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
-tests/cases/conformance/node/index.cts(83,21): error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
-tests/cases/conformance/node/index.cts(84,21): error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
-tests/cases/conformance/node/index.cts(85,21): error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+tests/cases/conformance/node/index.cts(76,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
+tests/cases/conformance/node/index.cts(77,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.cts(78,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.cts(79,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
+tests/cases/conformance/node/index.cts(80,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.cts(81,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.cts(82,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
+tests/cases/conformance/node/index.cts(83,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.cts(84,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.cts(85,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
 tests/cases/conformance/node/index.mts(14,22): error TS2307: Cannot find module './' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(15,22): error TS2307: Cannot find module './index' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(16,22): error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(17,22): error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(18,22): error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(19,22): error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(20,22): error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(21,22): error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(22,22): error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(23,22): error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(24,22): error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+tests/cases/conformance/node/index.mts(15,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
+tests/cases/conformance/node/index.mts(16,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(17,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(18,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
+tests/cases/conformance/node/index.mts(19,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(20,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(21,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
+tests/cases/conformance/node/index.mts(22,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(23,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(24,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
 tests/cases/conformance/node/index.mts(50,22): error TS1471: Module './' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.mts(51,22): error TS1471: Module './index' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.mts(58,22): error TS1471: Module './subfolder2/another' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.mts(59,22): error TS1471: Module './subfolder2/another/' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.mts(60,22): error TS1471: Module './subfolder2/another/index' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.mts(74,21): error TS2307: Cannot find module './' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(75,21): error TS2307: Cannot find module './index' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(76,21): error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(77,21): error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(78,21): error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(79,21): error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(80,21): error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(81,21): error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(82,21): error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(83,21): error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(84,21): error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+tests/cases/conformance/node/index.mts(75,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
+tests/cases/conformance/node/index.mts(76,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(77,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(78,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
+tests/cases/conformance/node/index.mts(79,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(80,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(81,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
+tests/cases/conformance/node/index.mts(82,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(83,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(84,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
 tests/cases/conformance/node/index.ts(14,22): error TS2307: Cannot find module './' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(15,22): error TS2307: Cannot find module './index' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(16,22): error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(17,22): error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(18,22): error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(19,22): error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(20,22): error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(21,22): error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(22,22): error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(23,22): error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(24,22): error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+tests/cases/conformance/node/index.ts(15,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
+tests/cases/conformance/node/index.ts(16,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(17,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(18,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
+tests/cases/conformance/node/index.ts(19,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(20,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(21,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
+tests/cases/conformance/node/index.ts(22,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(23,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(24,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
 tests/cases/conformance/node/index.ts(50,22): error TS1471: Module './' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.ts(51,22): error TS1471: Module './index' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.ts(58,22): error TS1471: Module './subfolder2/another' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.ts(59,22): error TS1471: Module './subfolder2/another/' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.ts(60,22): error TS1471: Module './subfolder2/another/index' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.ts(74,21): error TS2307: Cannot find module './' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(75,21): error TS2307: Cannot find module './index' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(76,21): error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(77,21): error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(78,21): error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(79,21): error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(80,21): error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(81,21): error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(82,21): error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(83,21): error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(84,21): error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+tests/cases/conformance/node/index.ts(75,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
+tests/cases/conformance/node/index.ts(76,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(77,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(78,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
+tests/cases/conformance/node/index.ts(79,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(80,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(81,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
+tests/cases/conformance/node/index.ts(82,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(83,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(84,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
 
 
 ==== tests/cases/conformance/node/subfolder/index.ts (0 errors) ====
@@ -136,34 +136,34 @@ tests/cases/conformance/node/index.ts(84,21): error TS2307: Cannot find module '
 !!! error TS2307: Cannot find module './' or its corresponding type declarations.
     import * as m14 from "./index";
                          ~~~~~~~~~
-!!! error TS2307: Cannot find module './index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
     import * as m15 from "./subfolder";
                          ~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m16 from "./subfolder/";
                          ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m17 from "./subfolder/index";
                          ~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
     import * as m18 from "./subfolder2";
                          ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m19 from "./subfolder2/";
                          ~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m20 from "./subfolder2/index";
                          ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
     import * as m21 from "./subfolder2/another";
                          ~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m22 from "./subfolder2/another/";
                          ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m23 from "./subfolder2/another/index";
                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
     void m1;
     void m2;
     void m3;
@@ -228,34 +228,34 @@ tests/cases/conformance/node/index.ts(84,21): error TS2307: Cannot find module '
 !!! error TS2307: Cannot find module './' or its corresponding type declarations.
     const _m36 = import("./index");
                         ~~~~~~~~~
-!!! error TS2307: Cannot find module './index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
     const _m37 = import("./subfolder");
                         ~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m38 = import("./subfolder/");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m39 = import("./subfolder/index");
                         ~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
     const _m40 = import("./subfolder2");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m41 = import("./subfolder2/");
                         ~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m42 = import("./subfolder2/index");
                         ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
     const _m43 = import("./subfolder2/another");
                         ~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m44 = import("./subfolder2/another/");
                         ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m45 = import("./subfolder2/another/index");
                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
     
     // esm format file
     const x = 1;
@@ -372,34 +372,34 @@ tests/cases/conformance/node/index.ts(84,21): error TS2307: Cannot find module '
 !!! error TS2307: Cannot find module './' or its corresponding type declarations.
     const _m36 = import("./index");
                         ~~~~~~~~~
-!!! error TS2307: Cannot find module './index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
     const _m37 = import("./subfolder");
                         ~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m38 = import("./subfolder/");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m39 = import("./subfolder/index");
                         ~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
     const _m40 = import("./subfolder2");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m41 = import("./subfolder2/");
                         ~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m42 = import("./subfolder2/index");
                         ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
     const _m43 = import("./subfolder2/another");
                         ~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m44 = import("./subfolder2/another/");
                         ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m45 = import("./subfolder2/another/index");
                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
     // cjs format file
     const x = 1;
     export {x};
@@ -422,34 +422,34 @@ tests/cases/conformance/node/index.ts(84,21): error TS2307: Cannot find module '
 !!! error TS2307: Cannot find module './' or its corresponding type declarations.
     import * as m14 from "./index";
                          ~~~~~~~~~
-!!! error TS2307: Cannot find module './index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
     import * as m15 from "./subfolder";
                          ~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m16 from "./subfolder/";
                          ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m17 from "./subfolder/index";
                          ~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
     import * as m18 from "./subfolder2";
                          ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m19 from "./subfolder2/";
                          ~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m20 from "./subfolder2/index";
                          ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
     import * as m21 from "./subfolder2/another";
                          ~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m22 from "./subfolder2/another/";
                          ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m23 from "./subfolder2/another/index";
                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
     void m1;
     void m2;
     void m3;
@@ -514,34 +514,34 @@ tests/cases/conformance/node/index.ts(84,21): error TS2307: Cannot find module '
 !!! error TS2307: Cannot find module './' or its corresponding type declarations.
     const _m36 = import("./index");
                         ~~~~~~~~~
-!!! error TS2307: Cannot find module './index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
     const _m37 = import("./subfolder");
                         ~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m38 = import("./subfolder/");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m39 = import("./subfolder/index");
                         ~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
     const _m40 = import("./subfolder2");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m41 = import("./subfolder2/");
                         ~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m42 = import("./subfolder2/index");
                         ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
     const _m43 = import("./subfolder2/another");
                         ~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m44 = import("./subfolder2/another/");
                         ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m45 = import("./subfolder2/another/index");
                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
     // esm format file
     const x = 1;
     export {x};
diff --git a/tests/baselines/reference/nodeModules1(module=nodenext).errors.txt b/tests/baselines/reference/nodeModules1(module=nodenext).errors.txt
index 6398640a86946..724e3b73ed7b2 100644
--- a/tests/baselines/reference/nodeModules1(module=nodenext).errors.txt
+++ b/tests/baselines/reference/nodeModules1(module=nodenext).errors.txt
@@ -15,70 +15,70 @@ tests/cases/conformance/node/index.cts(59,22): error TS1471: Module './subfolder
 tests/cases/conformance/node/index.cts(60,22): error TS1471: Module './subfolder2/another/' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.cts(61,22): error TS1471: Module './subfolder2/another/index' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.cts(75,21): error TS2307: Cannot find module './' or its corresponding type declarations.
-tests/cases/conformance/node/index.cts(76,21): error TS2307: Cannot find module './index' or its corresponding type declarations.
-tests/cases/conformance/node/index.cts(77,21): error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
-tests/cases/conformance/node/index.cts(78,21): error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
-tests/cases/conformance/node/index.cts(79,21): error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
-tests/cases/conformance/node/index.cts(80,21): error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
-tests/cases/conformance/node/index.cts(81,21): error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
-tests/cases/conformance/node/index.cts(82,21): error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
-tests/cases/conformance/node/index.cts(83,21): error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
-tests/cases/conformance/node/index.cts(84,21): error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
-tests/cases/conformance/node/index.cts(85,21): error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+tests/cases/conformance/node/index.cts(76,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
+tests/cases/conformance/node/index.cts(77,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.cts(78,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.cts(79,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
+tests/cases/conformance/node/index.cts(80,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.cts(81,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.cts(82,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
+tests/cases/conformance/node/index.cts(83,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.cts(84,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.cts(85,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
 tests/cases/conformance/node/index.mts(14,22): error TS2307: Cannot find module './' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(15,22): error TS2307: Cannot find module './index' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(16,22): error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(17,22): error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(18,22): error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(19,22): error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(20,22): error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(21,22): error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(22,22): error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(23,22): error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(24,22): error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+tests/cases/conformance/node/index.mts(15,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
+tests/cases/conformance/node/index.mts(16,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(17,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(18,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
+tests/cases/conformance/node/index.mts(19,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(20,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(21,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
+tests/cases/conformance/node/index.mts(22,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(23,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(24,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
 tests/cases/conformance/node/index.mts(50,22): error TS1471: Module './' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.mts(51,22): error TS1471: Module './index' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.mts(58,22): error TS1471: Module './subfolder2/another' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.mts(59,22): error TS1471: Module './subfolder2/another/' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.mts(60,22): error TS1471: Module './subfolder2/another/index' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.mts(74,21): error TS2307: Cannot find module './' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(75,21): error TS2307: Cannot find module './index' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(76,21): error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(77,21): error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(78,21): error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(79,21): error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(80,21): error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(81,21): error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(82,21): error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(83,21): error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
-tests/cases/conformance/node/index.mts(84,21): error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+tests/cases/conformance/node/index.mts(75,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
+tests/cases/conformance/node/index.mts(76,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(77,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(78,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
+tests/cases/conformance/node/index.mts(79,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(80,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(81,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
+tests/cases/conformance/node/index.mts(82,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(83,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.mts(84,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
 tests/cases/conformance/node/index.ts(14,22): error TS2307: Cannot find module './' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(15,22): error TS2307: Cannot find module './index' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(16,22): error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(17,22): error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(18,22): error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(19,22): error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(20,22): error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(21,22): error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(22,22): error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(23,22): error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(24,22): error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+tests/cases/conformance/node/index.ts(15,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
+tests/cases/conformance/node/index.ts(16,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(17,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(18,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
+tests/cases/conformance/node/index.ts(19,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(20,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(21,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
+tests/cases/conformance/node/index.ts(22,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(23,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(24,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
 tests/cases/conformance/node/index.ts(50,22): error TS1471: Module './' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.ts(51,22): error TS1471: Module './index' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.ts(58,22): error TS1471: Module './subfolder2/another' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.ts(59,22): error TS1471: Module './subfolder2/another/' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.ts(60,22): error TS1471: Module './subfolder2/another/index' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.ts(74,21): error TS2307: Cannot find module './' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(75,21): error TS2307: Cannot find module './index' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(76,21): error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(77,21): error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(78,21): error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(79,21): error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(80,21): error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(81,21): error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(82,21): error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(83,21): error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
-tests/cases/conformance/node/index.ts(84,21): error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+tests/cases/conformance/node/index.ts(75,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
+tests/cases/conformance/node/index.ts(76,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(77,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(78,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
+tests/cases/conformance/node/index.ts(79,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(80,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(81,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
+tests/cases/conformance/node/index.ts(82,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(83,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/index.ts(84,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
 
 
 ==== tests/cases/conformance/node/subfolder/index.ts (0 errors) ====
@@ -136,34 +136,34 @@ tests/cases/conformance/node/index.ts(84,21): error TS2307: Cannot find module '
 !!! error TS2307: Cannot find module './' or its corresponding type declarations.
     import * as m14 from "./index";
                          ~~~~~~~~~
-!!! error TS2307: Cannot find module './index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
     import * as m15 from "./subfolder";
                          ~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m16 from "./subfolder/";
                          ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m17 from "./subfolder/index";
                          ~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
     import * as m18 from "./subfolder2";
                          ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m19 from "./subfolder2/";
                          ~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m20 from "./subfolder2/index";
                          ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
     import * as m21 from "./subfolder2/another";
                          ~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m22 from "./subfolder2/another/";
                          ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m23 from "./subfolder2/another/index";
                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
     void m1;
     void m2;
     void m3;
@@ -228,34 +228,34 @@ tests/cases/conformance/node/index.ts(84,21): error TS2307: Cannot find module '
 !!! error TS2307: Cannot find module './' or its corresponding type declarations.
     const _m36 = import("./index");
                         ~~~~~~~~~
-!!! error TS2307: Cannot find module './index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
     const _m37 = import("./subfolder");
                         ~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m38 = import("./subfolder/");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m39 = import("./subfolder/index");
                         ~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
     const _m40 = import("./subfolder2");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m41 = import("./subfolder2/");
                         ~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m42 = import("./subfolder2/index");
                         ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
     const _m43 = import("./subfolder2/another");
                         ~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m44 = import("./subfolder2/another/");
                         ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m45 = import("./subfolder2/another/index");
                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
     
     // esm format file
     const x = 1;
@@ -372,34 +372,34 @@ tests/cases/conformance/node/index.ts(84,21): error TS2307: Cannot find module '
 !!! error TS2307: Cannot find module './' or its corresponding type declarations.
     const _m36 = import("./index");
                         ~~~~~~~~~
-!!! error TS2307: Cannot find module './index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
     const _m37 = import("./subfolder");
                         ~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m38 = import("./subfolder/");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m39 = import("./subfolder/index");
                         ~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
     const _m40 = import("./subfolder2");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m41 = import("./subfolder2/");
                         ~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m42 = import("./subfolder2/index");
                         ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
     const _m43 = import("./subfolder2/another");
                         ~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m44 = import("./subfolder2/another/");
                         ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m45 = import("./subfolder2/another/index");
                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
     // cjs format file
     const x = 1;
     export {x};
@@ -422,34 +422,34 @@ tests/cases/conformance/node/index.ts(84,21): error TS2307: Cannot find module '
 !!! error TS2307: Cannot find module './' or its corresponding type declarations.
     import * as m14 from "./index";
                          ~~~~~~~~~
-!!! error TS2307: Cannot find module './index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
     import * as m15 from "./subfolder";
                          ~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m16 from "./subfolder/";
                          ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m17 from "./subfolder/index";
                          ~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
     import * as m18 from "./subfolder2";
                          ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m19 from "./subfolder2/";
                          ~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m20 from "./subfolder2/index";
                          ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
     import * as m21 from "./subfolder2/another";
                          ~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m22 from "./subfolder2/another/";
                          ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m23 from "./subfolder2/another/index";
                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
     void m1;
     void m2;
     void m3;
@@ -514,34 +514,34 @@ tests/cases/conformance/node/index.ts(84,21): error TS2307: Cannot find module '
 !!! error TS2307: Cannot find module './' or its corresponding type declarations.
     const _m36 = import("./index");
                         ~~~~~~~~~
-!!! error TS2307: Cannot find module './index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
     const _m37 = import("./subfolder");
                         ~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m38 = import("./subfolder/");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m39 = import("./subfolder/index");
                         ~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
     const _m40 = import("./subfolder2");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m41 = import("./subfolder2/");
                         ~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m42 = import("./subfolder2/index");
                         ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
     const _m43 = import("./subfolder2/another");
                         ~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m44 = import("./subfolder2/another/");
                         ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m45 = import("./subfolder2/another/index");
                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
     // esm format file
     const x = 1;
     export {x};
diff --git a/tests/baselines/reference/nodeModulesAllowJs1(module=node12).errors.txt b/tests/baselines/reference/nodeModulesAllowJs1(module=node12).errors.txt
index 099485a317c49..178c28ed46004 100644
--- a/tests/baselines/reference/nodeModulesAllowJs1(module=node12).errors.txt
+++ b/tests/baselines/reference/nodeModulesAllowJs1(module=node12).errors.txt
@@ -26,27 +26,27 @@ tests/cases/conformance/node/allowJs/index.cjs(60,22): error TS1471: Module './s
 tests/cases/conformance/node/allowJs/index.cjs(61,1): error TS8002: 'import ... =' can only be used in TypeScript files.
 tests/cases/conformance/node/allowJs/index.cjs(61,22): error TS1471: Module './subfolder2/another/index' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/allowJs/index.cjs(75,21): error TS2307: Cannot find module './' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.cjs(76,21): error TS2307: Cannot find module './index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.cjs(77,21): error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.cjs(78,21): error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.cjs(79,21): error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.cjs(80,21): error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.cjs(81,21): error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.cjs(82,21): error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.cjs(83,21): error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.cjs(84,21): error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.cjs(85,21): error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+tests/cases/conformance/node/allowJs/index.cjs(76,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
+tests/cases/conformance/node/allowJs/index.cjs(77,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.cjs(78,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.cjs(79,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
+tests/cases/conformance/node/allowJs/index.cjs(80,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.cjs(81,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.cjs(82,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
+tests/cases/conformance/node/allowJs/index.cjs(83,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.cjs(84,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.cjs(85,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
 tests/cases/conformance/node/allowJs/index.js(14,22): error TS2307: Cannot find module './' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(15,22): error TS2307: Cannot find module './index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(16,22): error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(17,22): error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(18,22): error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(19,22): error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(20,22): error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(21,22): error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(22,22): error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(23,22): error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(24,22): error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+tests/cases/conformance/node/allowJs/index.js(15,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
+tests/cases/conformance/node/allowJs/index.js(16,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(17,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(18,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
+tests/cases/conformance/node/allowJs/index.js(19,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(20,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(21,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
+tests/cases/conformance/node/allowJs/index.js(22,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(23,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(24,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
 tests/cases/conformance/node/allowJs/index.js(50,1): error TS8002: 'import ... =' can only be used in TypeScript files.
 tests/cases/conformance/node/allowJs/index.js(50,22): error TS1471: Module './' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/allowJs/index.js(51,1): error TS8002: 'import ... =' can only be used in TypeScript files.
@@ -64,27 +64,27 @@ tests/cases/conformance/node/allowJs/index.js(59,22): error TS1471: Module './su
 tests/cases/conformance/node/allowJs/index.js(60,1): error TS8002: 'import ... =' can only be used in TypeScript files.
 tests/cases/conformance/node/allowJs/index.js(60,22): error TS1471: Module './subfolder2/another/index' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/allowJs/index.js(74,21): error TS2307: Cannot find module './' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(75,21): error TS2307: Cannot find module './index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(76,21): error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(77,21): error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(78,21): error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(79,21): error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(80,21): error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(81,21): error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(82,21): error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(83,21): error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(84,21): error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+tests/cases/conformance/node/allowJs/index.js(75,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
+tests/cases/conformance/node/allowJs/index.js(76,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(77,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(78,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
+tests/cases/conformance/node/allowJs/index.js(79,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(80,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(81,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
+tests/cases/conformance/node/allowJs/index.js(82,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(83,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(84,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
 tests/cases/conformance/node/allowJs/index.mjs(14,22): error TS2307: Cannot find module './' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(15,22): error TS2307: Cannot find module './index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(16,22): error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(17,22): error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(18,22): error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(19,22): error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(20,22): error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(21,22): error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(22,22): error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(23,22): error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(24,22): error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+tests/cases/conformance/node/allowJs/index.mjs(15,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
+tests/cases/conformance/node/allowJs/index.mjs(16,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(17,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(18,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
+tests/cases/conformance/node/allowJs/index.mjs(19,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(20,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(21,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
+tests/cases/conformance/node/allowJs/index.mjs(22,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(23,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(24,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
 tests/cases/conformance/node/allowJs/index.mjs(50,1): error TS8002: 'import ... =' can only be used in TypeScript files.
 tests/cases/conformance/node/allowJs/index.mjs(50,22): error TS1471: Module './' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/allowJs/index.mjs(51,1): error TS8002: 'import ... =' can only be used in TypeScript files.
@@ -102,16 +102,16 @@ tests/cases/conformance/node/allowJs/index.mjs(59,22): error TS1471: Module './s
 tests/cases/conformance/node/allowJs/index.mjs(60,1): error TS8002: 'import ... =' can only be used in TypeScript files.
 tests/cases/conformance/node/allowJs/index.mjs(60,22): error TS1471: Module './subfolder2/another/index' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/allowJs/index.mjs(74,21): error TS2307: Cannot find module './' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(75,21): error TS2307: Cannot find module './index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(76,21): error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(77,21): error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(78,21): error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(79,21): error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(80,21): error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(81,21): error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(82,21): error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(83,21): error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(84,21): error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+tests/cases/conformance/node/allowJs/index.mjs(75,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
+tests/cases/conformance/node/allowJs/index.mjs(76,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(77,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(78,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
+tests/cases/conformance/node/allowJs/index.mjs(79,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(80,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(81,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
+tests/cases/conformance/node/allowJs/index.mjs(82,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(83,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(84,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
 
 
 ==== tests/cases/conformance/node/allowJs/subfolder/index.js (0 errors) ====
@@ -169,34 +169,34 @@ tests/cases/conformance/node/allowJs/index.mjs(84,21): error TS2307: Cannot find
 !!! error TS2307: Cannot find module './' or its corresponding type declarations.
     import * as m14 from "./index";
                          ~~~~~~~~~
-!!! error TS2307: Cannot find module './index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
     import * as m15 from "./subfolder";
                          ~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m16 from "./subfolder/";
                          ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m17 from "./subfolder/index";
                          ~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
     import * as m18 from "./subfolder2";
                          ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m19 from "./subfolder2/";
                          ~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m20 from "./subfolder2/index";
                          ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
     import * as m21 from "./subfolder2/another";
                          ~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m22 from "./subfolder2/another/";
                          ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m23 from "./subfolder2/another/index";
                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
     void m1;
     void m2;
     void m3;
@@ -283,34 +283,34 @@ tests/cases/conformance/node/allowJs/index.mjs(84,21): error TS2307: Cannot find
 !!! error TS2307: Cannot find module './' or its corresponding type declarations.
     const _m36 = import("./index");
                         ~~~~~~~~~
-!!! error TS2307: Cannot find module './index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
     const _m37 = import("./subfolder");
                         ~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m38 = import("./subfolder/");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m39 = import("./subfolder/index");
                         ~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
     const _m40 = import("./subfolder2");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m41 = import("./subfolder2/");
                         ~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m42 = import("./subfolder2/index");
                         ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
     const _m43 = import("./subfolder2/another");
                         ~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m44 = import("./subfolder2/another/");
                         ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m45 = import("./subfolder2/another/index");
                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
     // esm format file
     const x = 1;
     export {x};
@@ -448,34 +448,34 @@ tests/cases/conformance/node/allowJs/index.mjs(84,21): error TS2307: Cannot find
 !!! error TS2307: Cannot find module './' or its corresponding type declarations.
     const _m36 = import("./index");
                         ~~~~~~~~~
-!!! error TS2307: Cannot find module './index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
     const _m37 = import("./subfolder");
                         ~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m38 = import("./subfolder/");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m39 = import("./subfolder/index");
                         ~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
     const _m40 = import("./subfolder2");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m41 = import("./subfolder2/");
                         ~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m42 = import("./subfolder2/index");
                         ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
     const _m43 = import("./subfolder2/another");
                         ~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m44 = import("./subfolder2/another/");
                         ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m45 = import("./subfolder2/another/index");
                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
     // cjs format file
     const x = 1;
     export {x};
@@ -498,34 +498,34 @@ tests/cases/conformance/node/allowJs/index.mjs(84,21): error TS2307: Cannot find
 !!! error TS2307: Cannot find module './' or its corresponding type declarations.
     import * as m14 from "./index";
                          ~~~~~~~~~
-!!! error TS2307: Cannot find module './index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
     import * as m15 from "./subfolder";
                          ~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m16 from "./subfolder/";
                          ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m17 from "./subfolder/index";
                          ~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
     import * as m18 from "./subfolder2";
                          ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m19 from "./subfolder2/";
                          ~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m20 from "./subfolder2/index";
                          ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
     import * as m21 from "./subfolder2/another";
                          ~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m22 from "./subfolder2/another/";
                          ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m23 from "./subfolder2/another/index";
                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
     void m1;
     void m2;
     void m3;
@@ -612,34 +612,34 @@ tests/cases/conformance/node/allowJs/index.mjs(84,21): error TS2307: Cannot find
 !!! error TS2307: Cannot find module './' or its corresponding type declarations.
     const _m36 = import("./index");
                         ~~~~~~~~~
-!!! error TS2307: Cannot find module './index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
     const _m37 = import("./subfolder");
                         ~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m38 = import("./subfolder/");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m39 = import("./subfolder/index");
                         ~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
     const _m40 = import("./subfolder2");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m41 = import("./subfolder2/");
                         ~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m42 = import("./subfolder2/index");
                         ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
     const _m43 = import("./subfolder2/another");
                         ~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m44 = import("./subfolder2/another/");
                         ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m45 = import("./subfolder2/another/index");
                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
     
     // esm format file
     const x = 1;
diff --git a/tests/baselines/reference/nodeModulesAllowJs1(module=nodenext).errors.txt b/tests/baselines/reference/nodeModulesAllowJs1(module=nodenext).errors.txt
index 099485a317c49..178c28ed46004 100644
--- a/tests/baselines/reference/nodeModulesAllowJs1(module=nodenext).errors.txt
+++ b/tests/baselines/reference/nodeModulesAllowJs1(module=nodenext).errors.txt
@@ -26,27 +26,27 @@ tests/cases/conformance/node/allowJs/index.cjs(60,22): error TS1471: Module './s
 tests/cases/conformance/node/allowJs/index.cjs(61,1): error TS8002: 'import ... =' can only be used in TypeScript files.
 tests/cases/conformance/node/allowJs/index.cjs(61,22): error TS1471: Module './subfolder2/another/index' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/allowJs/index.cjs(75,21): error TS2307: Cannot find module './' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.cjs(76,21): error TS2307: Cannot find module './index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.cjs(77,21): error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.cjs(78,21): error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.cjs(79,21): error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.cjs(80,21): error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.cjs(81,21): error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.cjs(82,21): error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.cjs(83,21): error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.cjs(84,21): error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.cjs(85,21): error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+tests/cases/conformance/node/allowJs/index.cjs(76,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
+tests/cases/conformance/node/allowJs/index.cjs(77,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.cjs(78,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.cjs(79,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
+tests/cases/conformance/node/allowJs/index.cjs(80,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.cjs(81,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.cjs(82,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
+tests/cases/conformance/node/allowJs/index.cjs(83,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.cjs(84,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.cjs(85,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
 tests/cases/conformance/node/allowJs/index.js(14,22): error TS2307: Cannot find module './' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(15,22): error TS2307: Cannot find module './index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(16,22): error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(17,22): error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(18,22): error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(19,22): error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(20,22): error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(21,22): error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(22,22): error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(23,22): error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(24,22): error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+tests/cases/conformance/node/allowJs/index.js(15,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
+tests/cases/conformance/node/allowJs/index.js(16,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(17,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(18,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
+tests/cases/conformance/node/allowJs/index.js(19,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(20,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(21,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
+tests/cases/conformance/node/allowJs/index.js(22,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(23,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(24,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
 tests/cases/conformance/node/allowJs/index.js(50,1): error TS8002: 'import ... =' can only be used in TypeScript files.
 tests/cases/conformance/node/allowJs/index.js(50,22): error TS1471: Module './' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/allowJs/index.js(51,1): error TS8002: 'import ... =' can only be used in TypeScript files.
@@ -64,27 +64,27 @@ tests/cases/conformance/node/allowJs/index.js(59,22): error TS1471: Module './su
 tests/cases/conformance/node/allowJs/index.js(60,1): error TS8002: 'import ... =' can only be used in TypeScript files.
 tests/cases/conformance/node/allowJs/index.js(60,22): error TS1471: Module './subfolder2/another/index' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/allowJs/index.js(74,21): error TS2307: Cannot find module './' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(75,21): error TS2307: Cannot find module './index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(76,21): error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(77,21): error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(78,21): error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(79,21): error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(80,21): error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(81,21): error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(82,21): error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(83,21): error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.js(84,21): error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+tests/cases/conformance/node/allowJs/index.js(75,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
+tests/cases/conformance/node/allowJs/index.js(76,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(77,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(78,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
+tests/cases/conformance/node/allowJs/index.js(79,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(80,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(81,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
+tests/cases/conformance/node/allowJs/index.js(82,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(83,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.js(84,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
 tests/cases/conformance/node/allowJs/index.mjs(14,22): error TS2307: Cannot find module './' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(15,22): error TS2307: Cannot find module './index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(16,22): error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(17,22): error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(18,22): error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(19,22): error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(20,22): error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(21,22): error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(22,22): error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(23,22): error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(24,22): error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+tests/cases/conformance/node/allowJs/index.mjs(15,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
+tests/cases/conformance/node/allowJs/index.mjs(16,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(17,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(18,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
+tests/cases/conformance/node/allowJs/index.mjs(19,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(20,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(21,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
+tests/cases/conformance/node/allowJs/index.mjs(22,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(23,22): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(24,22): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
 tests/cases/conformance/node/allowJs/index.mjs(50,1): error TS8002: 'import ... =' can only be used in TypeScript files.
 tests/cases/conformance/node/allowJs/index.mjs(50,22): error TS1471: Module './' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/allowJs/index.mjs(51,1): error TS8002: 'import ... =' can only be used in TypeScript files.
@@ -102,16 +102,16 @@ tests/cases/conformance/node/allowJs/index.mjs(59,22): error TS1471: Module './s
 tests/cases/conformance/node/allowJs/index.mjs(60,1): error TS8002: 'import ... =' can only be used in TypeScript files.
 tests/cases/conformance/node/allowJs/index.mjs(60,22): error TS1471: Module './subfolder2/another/index' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/allowJs/index.mjs(74,21): error TS2307: Cannot find module './' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(75,21): error TS2307: Cannot find module './index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(76,21): error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(77,21): error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(78,21): error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(79,21): error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(80,21): error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(81,21): error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(82,21): error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(83,21): error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
-tests/cases/conformance/node/allowJs/index.mjs(84,21): error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+tests/cases/conformance/node/allowJs/index.mjs(75,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
+tests/cases/conformance/node/allowJs/index.mjs(76,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(77,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(78,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
+tests/cases/conformance/node/allowJs/index.mjs(79,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(80,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(81,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
+tests/cases/conformance/node/allowJs/index.mjs(82,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(83,21): error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
+tests/cases/conformance/node/allowJs/index.mjs(84,21): error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
 
 
 ==== tests/cases/conformance/node/allowJs/subfolder/index.js (0 errors) ====
@@ -169,34 +169,34 @@ tests/cases/conformance/node/allowJs/index.mjs(84,21): error TS2307: Cannot find
 !!! error TS2307: Cannot find module './' or its corresponding type declarations.
     import * as m14 from "./index";
                          ~~~~~~~~~
-!!! error TS2307: Cannot find module './index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
     import * as m15 from "./subfolder";
                          ~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m16 from "./subfolder/";
                          ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m17 from "./subfolder/index";
                          ~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
     import * as m18 from "./subfolder2";
                          ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m19 from "./subfolder2/";
                          ~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m20 from "./subfolder2/index";
                          ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
     import * as m21 from "./subfolder2/another";
                          ~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m22 from "./subfolder2/another/";
                          ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m23 from "./subfolder2/another/index";
                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
     void m1;
     void m2;
     void m3;
@@ -283,34 +283,34 @@ tests/cases/conformance/node/allowJs/index.mjs(84,21): error TS2307: Cannot find
 !!! error TS2307: Cannot find module './' or its corresponding type declarations.
     const _m36 = import("./index");
                         ~~~~~~~~~
-!!! error TS2307: Cannot find module './index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
     const _m37 = import("./subfolder");
                         ~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m38 = import("./subfolder/");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m39 = import("./subfolder/index");
                         ~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
     const _m40 = import("./subfolder2");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m41 = import("./subfolder2/");
                         ~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m42 = import("./subfolder2/index");
                         ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
     const _m43 = import("./subfolder2/another");
                         ~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m44 = import("./subfolder2/another/");
                         ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m45 = import("./subfolder2/another/index");
                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
     // esm format file
     const x = 1;
     export {x};
@@ -448,34 +448,34 @@ tests/cases/conformance/node/allowJs/index.mjs(84,21): error TS2307: Cannot find
 !!! error TS2307: Cannot find module './' or its corresponding type declarations.
     const _m36 = import("./index");
                         ~~~~~~~~~
-!!! error TS2307: Cannot find module './index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
     const _m37 = import("./subfolder");
                         ~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m38 = import("./subfolder/");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m39 = import("./subfolder/index");
                         ~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
     const _m40 = import("./subfolder2");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m41 = import("./subfolder2/");
                         ~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m42 = import("./subfolder2/index");
                         ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
     const _m43 = import("./subfolder2/another");
                         ~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m44 = import("./subfolder2/another/");
                         ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m45 = import("./subfolder2/another/index");
                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
     // cjs format file
     const x = 1;
     export {x};
@@ -498,34 +498,34 @@ tests/cases/conformance/node/allowJs/index.mjs(84,21): error TS2307: Cannot find
 !!! error TS2307: Cannot find module './' or its corresponding type declarations.
     import * as m14 from "./index";
                          ~~~~~~~~~
-!!! error TS2307: Cannot find module './index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
     import * as m15 from "./subfolder";
                          ~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m16 from "./subfolder/";
                          ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m17 from "./subfolder/index";
                          ~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
     import * as m18 from "./subfolder2";
                          ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m19 from "./subfolder2/";
                          ~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m20 from "./subfolder2/index";
                          ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
     import * as m21 from "./subfolder2/another";
                          ~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m22 from "./subfolder2/another/";
                          ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     import * as m23 from "./subfolder2/another/index";
                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
     void m1;
     void m2;
     void m3;
@@ -612,34 +612,34 @@ tests/cases/conformance/node/allowJs/index.mjs(84,21): error TS2307: Cannot find
 !!! error TS2307: Cannot find module './' or its corresponding type declarations.
     const _m36 = import("./index");
                         ~~~~~~~~~
-!!! error TS2307: Cannot find module './index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './index.mjs'?
     const _m37 = import("./subfolder");
                         ~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m38 = import("./subfolder/");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m39 = import("./subfolder/index");
                         ~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder/index.mjs'?
     const _m40 = import("./subfolder2");
                         ~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m41 = import("./subfolder2/");
                         ~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m42 = import("./subfolder2/index");
                         ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/index.mjs'?
     const _m43 = import("./subfolder2/another");
                         ~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m44 = import("./subfolder2/another/");
                         ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/' or its corresponding type declarations.
+!!! error TS2834: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Consider adding an extension to the import path.
     const _m45 = import("./subfolder2/another/index");
                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './subfolder2/another/index' or its corresponding type declarations.
+!!! error TS2835: Relative import paths need explicit file extensions in EcmaScript imports when '--moduleResolution' is 'node12' or 'nodenext'. Did you mean './subfolder2/another/index.mjs'?
     
     // esm format file
     const x = 1;
diff --git a/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension1.ts b/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension1.ts
new file mode 100644
index 0000000000000..83e86fc6c6069
--- /dev/null
+++ b/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension1.ts
@@ -0,0 +1,12 @@
+// @moduleResolution: node12
+// @module: node12
+
+// @filename: /src/foo.mts
+export function foo() {
+    return "";
+}
+
+// @filename: /src/bar.mts
+// Extensionless relative path ES import in an ES module
+import { foo } from "./foo"; // should error, suggest adding ".mjs"
+import { baz } from "./baz"; // should error, ask for extension, no extension suggestion
diff --git a/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension2.ts b/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension2.ts
new file mode 100644
index 0000000000000..0051e17401c7c
--- /dev/null
+++ b/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension2.ts
@@ -0,0 +1,6 @@
+// @moduleResolution: node12
+// @module: node12
+
+// @filename: /src/buzz.mts
+// Extensionless relative path cjs import in an ES module
+import foo = require("./foo"); // should error, should not ask for extension
\ No newline at end of file
diff --git a/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension3.ts b/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension3.ts
new file mode 100644
index 0000000000000..2ec3ff1ad0116
--- /dev/null
+++ b/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension3.ts
@@ -0,0 +1,12 @@
+// @moduleResolution: nodenext
+// @module: nodenext
+// @jsx: preserve
+
+// @filename: /src/foo.tsx
+export function foo() {
+    return "";
+}
+
+// @filename: /src/bar.mts
+// Extensionless relative path ES import in an ES module
+import { foo } from "./foo"; // should error, suggest adding ".jsx"
diff --git a/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension4.ts b/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension4.ts
new file mode 100644
index 0000000000000..c1eab70f92d82
--- /dev/null
+++ b/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension4.ts
@@ -0,0 +1,12 @@
+// @moduleResolution: nodenext
+// @module: nodenext
+// @jsx: react
+
+// @filename: /src/foo.tsx
+export function foo() {
+    return "";
+}
+
+// @filename: /src/bar.mts
+// Extensionless relative path ES import in an ES module
+import { foo } from "./foo"; // should error, suggest adding ".js"
diff --git a/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension5.ts b/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension5.ts
new file mode 100644
index 0000000000000..5053a242cd5d5
--- /dev/null
+++ b/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension5.ts
@@ -0,0 +1,6 @@
+// @moduleResolution: node12
+// @module: node12
+
+// @filename: /src/buzz.mts
+// Extensionless relative path dynamic import in an ES module
+import("./foo").then(x => x); // should error, ask for extension
\ No newline at end of file
diff --git a/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension6.ts b/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension6.ts
new file mode 100644
index 0000000000000..2a6ef2645dd4d
--- /dev/null
+++ b/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension6.ts
@@ -0,0 +1,8 @@
+// @moduleResolution: node12
+// @module: node12
+
+// @filename: /src/bar.cts
+// Extensionless relative path import statement in a cjs module
+// Import statements are not allowed in cjs files,
+// but other errors should not assume that they are allowed
+import { foo } from "./foo"; // should error, should not ask for extension
\ No newline at end of file
diff --git a/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension7.ts b/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension7.ts
new file mode 100644
index 0000000000000..3b10dd6e48aab
--- /dev/null
+++ b/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension7.ts
@@ -0,0 +1,6 @@
+// @moduleResolution: node12
+// @module: node12
+
+// @filename: /src/bar.cts
+// Extensionless relative path cjs import in a cjs module
+import foo = require("./foo"); // should error, should not ask for extension
\ No newline at end of file
diff --git a/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension8.ts b/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension8.ts
new file mode 100644
index 0000000000000..fef17b3aa1e54
--- /dev/null
+++ b/tests/cases/conformance/externalModules/moduleResolutionWithoutExtension8.ts
@@ -0,0 +1,6 @@
+// @moduleResolution: node12
+// @module: node12
+
+// @filename: /src/bar.cts
+// Extensionless relative path dynamic import in a cjs module
+import("./foo").then(x => x); // should error, ask for extension
\ No newline at end of file